Electroosmotically driven microfluidic actuators

A prototype electroactive polymer actuator has been developed based on electroosmotic (EO) pumping to create hydraulic pressure. The actuator was fabricated from poly(dimethylsiloxane) (PDMS) with embedded micro-scale channels, reservoirs, and electrodes surmounted by a membrane. An applied voltage caused one reservoir to expand as fluid was pumped into it, and the other reservoir to contract, with the membrane above the expansion reservoir rising by 400 μm within a few seconds. Since the prototype was made from PDMS, which is an elastomer, the device was entirely flexible. The actuator performance was characterized, and it agreed well with predicted values. Furthermore, the calculations indicate that, once optimized, such actuators could have high stress as well as high strain and high speed. By combining unit cells such as these into a material and actuating them individually via independently controlled flexible electrodes, one could realize smart materials that could change shape. Other future applications may include micro-valves, micro-positioners, soft robots, and active camouflage layers.